The present invention relates to a working machine, comprising a lift arm and an implement coupling, which is fixed to the lift arm and comprises a locking element, which is displaceable between an inoperative position and an operative position in which it is designed to shoot into a hole in an implement in order to lock this to the implement coupling.
The invention also relates to an implement locking element, which over a first section of its length has a first cross-sectional geometry that will allow this section of the locking element to shoot into a hole of given geometry defined by an implement.
The term working machine must be regarded as signifying and may include both mobile and stationary machines. A typical example of such a machine is a wheeled loader, on which it is desirable to have the facility for coupling and uncoupling an implement or switching between various implements.
The implement may be any form of implement. It is typically an implement for cultivating soil or for construction work, or for transporting material, such as an excavator shovel, a bulldozer shovel, a pallet fork or the like.
The term lift arm relates to arms which in some way permit raising or inclining of the implement coupling arranged at their ends, for locking an implement thereto.
As used in this context, therefore, the term lift arm encompasses not only arms, the primary function of which is to lift objects, but also other arms such as an arm, the primary function of which is to couple a plough or the like.
Arranging an implement coupling, on which different implements, such as an excavator shovel, a bulldozer shovel, a fork or the like, can be locked and released, that is to say detachably fitted on the lifting arm or arms of working machines such as wheeled loaders, primarily smaller-sized ones, is already known.
The implement is conventionally provided with two hooks situated horizontally in line with one another, and two horizontal lugs or rings, which each have holes situated horizontally in line with one another. The hooks are arranged vertically above and at a distance from the holes. The implement coupling comprises corresponding coupling members in the form of two fixed pins, on to which said hooks are hitched, and two displaceable pins situated in line, which by a horizontal translational movement are shot into the holes once the hooks have been hitched on to the fixed pins. The displaceable pins are preferably hydraulically powered.
Locking of the implement is usually done by an operator, who from an operating station, such as a driver's cab on the machine, guides the lift arm to a position in which the fixed pins of the implement coupling are made to engage with the hooks of the implement. The operator is normally able to verify visually that the hooks are engaged with the pins. Following this, or at the same time, the lift arm is guided so that said holes are situated in the position in which the displaceable pins can be shot through them, following which these pins, guided by controls located in the operating station, are hydraulically shot into the holes, thereby locking the implement to the implement coupling.
One problem on many working machines is that it is difficult for the operator, from the operating station, to visually verify whether the displaceable pins are actually engaged in the implement holes. It can happen that one or both of the pins misses the hole and merely bears against the material of the implement surrounding the hole and is therefore not displaced right into its operative engagement position. According to the prior art the pin has therefore been mechanically linked to a physical flag, which has shown whether or not the pin has been displaced into its operative position, that is to say far enough. A disadvantage with this known system, however, is that it can be unreliable in cases where dirt and other material occurring on the implement during operation prevent the flag from functioning or destroy it outright. Furthermore, such a flag will incorrectly indicate that coupling has occurred should the pin in question pass right beside the implement, that is to say when either the hole or the lug etc. in which the hole is situated, is struck by the pin. The pin will thereby be displaced right to the position which by definition is its operative position without any engagement with the implement hole occurring, the flag at the same time nevertheless falsely indicating that coupling has been effected.
It is desirable to provide a working machine with a construction which solves the aforementioned problems or at least facilitates a solution to these problems. The working machine should be designed so that it makes it possible to reliably determine that a displaceable locking element, corresponding to any of the above-mentioned displaceable pins, really is in effective engagement with an implement and shoots into holes arranged therein.
In so doing, the working machine should be designed so that it can be reliably determined that the locking element really has been displaced into the hole in question.
According to an aspect of the present invention, a working machine comprises a locking element having, over a first section of its length, a first cross-section which allows the first section of the locking element to be shot into a hole on an implement, and having over a second section, which adjoins the first section, a second cross-section which prevents the second section being shot further into said hole, the second section comprising a stop face designed to be brought to bear against the implement when securing the implement to the implement coupling. In other words, the second section projects radially from the first section to such an extent that once the first section has been introduced into the hole further displacement of the second section into a hole of given cross-section is prevented by the bearing face bearing against the implement material surrounding the hole. The term cross-section does not necessarily relate simply to shape, but may alternatively relate to size. The invention includes embodiments in which the first section and the second section have different or identical cross-sectional shapes, and different or identical sizes. A radially projecting stop face or bearing face is formed at the transition between said sections.
A prerequisite is thereby created allowing it to be determined whether the locking element has actually been fully displaced so that it engages in the hole in question. When the stop face encounters the implement, this can be suitably registered, for example by means of electrical sensors, as will be described later, and a signal indicating this relayed to an operator and displayed, for example, on an instrument panel in a driver's cab or the like.
In the circumferential direction of the locking element the stop face preferably extends only over a first part of the circumference of the locking element, whilst a second part of the outer circumference of the second section aligns with or extends radially inside a part of the outer circumference of the first section, viewed in the longitudinal direction of the locking element. The locking element should be located in the implement coupling in such a way that if the implement is situated right beside the locking element the implement can be allowed to slide with its outer periphery towards the locking element along the first section and the second section without the stop face being applied against the implement. The stop face may therefore typically be defined by a heel, which only extends along a part of the periphery of the locking element, viewed in the circumferential direction.
According to a preferred embodiment the locking element, in the absence of any contact between the stop face and the implement, is designed to be displaced into a position beyond the position corresponding to its operative position. In the case described above, in which the implement is situated right beside the locking element and its movement cannot be stopped by application of the stop face against the implement, it is thereby possible to register that this is the case, since it can be registered by means of sensors, as will be described later, that the locking element has been displaced past the position corresponding to its operative position.
According to an aspect of the present invention, an implement locking element includes, over a second section adjoining a first section, a second cross-section, which prevents the second section being shot into a hole, the second section comprising a stop face designed to be brought to bear against the implement.
An aspect of the invention furthermore relates to a method of detecting the attainment of a fixing position of a working machine according to the invention, wherein attainment of the bearing position is registered electronically. Registering of the attainment of the bearing position is preferably displayed electronically in a driver's cab of the working machine.